Competitive and allelopathic interference between soybean crop and annual wormwood (Artemisia annua L.) under field conditions     

C.M. Morvillo  E.B. de la Fuente  A. Gil  M.A. Martínez-Ghersa  J.L. González-Andújar 《European Journal of Agronomy》2011,34(4):211-221

Annual wormwood interference on soybean crop growth and yield may result from competition and allelopathy, which are modulated by crop management. Allelochemicals released by annual wormwood (e.g. artemisinin) may affect the crop directly or indirectly through the effect on the nitrogen fixing symbiont, Bradyrhizobium japonicum. The objectives were (i) to quantify the crop response (i.e. biomass production, nodulation and yield) to weed interference and (ii) to determinate the relative change of competition and allelopathy interferences, when a sublethal dose of herbicide is applied. Two split plot field experiments with three replications were used. The experiment involved a factorial combination of five weed–crop density (soybean/annual wormwood, plants m^?2) levels: D1, pure soybean, 40/0 plants m^?2; D2, 40/2 plants m^?2; D3, 40/4 plants m^?2 and D4, 40/8 plants m^?2, and D5, pure annual wormwood, 0/8 plants m^?2, two activated carbon (allelopathy) levels: C?, with activated carbon (reduced allelopathy) and C+, non activated carbon applied (with allelopathy) and two herbicide levels: H?, untreated and H+, treated with a sub-lethal dose of glyphosate. Activated carbon to adsorb allelochemicals (with and without activated carbon) and glyphosate application (with and no herbicide) were assigned to sub-plots. Increasing weed density did not affect crop biomass at flowering, but changed nodule number and soybean yield with a different pattern depending on carbon and herbicide treatment. Relative crop yield decreased with increasing relative weed biomass. This decrease was particularly drastic when allelopathy was reduced by activated carbon and without herbicide application. The maximum yield losses of 33% in 2006 and 17% in 2007 were observed with the highest weed density (8 plants m^?2). In contrast, without carbon (high allelopathy level), soybean yield remained stable within the explored range of annual wormwood biomass, despite the fact that weed biomass at high densities (D4) was high enough to generate competition. The lack of response to increasing weed density could be related to the indirect effect of allelochemicals interacting with soil microorganisms (i.e. B. japonicum) that positively affected the nodulation (e.g. larger nodules in 2006 and increased nodules biomass due to higher number of roots in 2007 at high densities). With herbicide application, soybean yield of both carbon treatments remained stable when biomass of annual wormwood increased. This research provided strong evidence in support of the existence of positive effect of allelopathic and competitive interactions between annual wormwood and soybean crop under field conditions that may be overridden under herbicide application.  相似文献   

A neoplastic gene fusion mimics trans-splicing of RNAs in normal human cells     

Li H  Wang J  Mor G  Sklar J 《Science (New York, N.Y.)》2008,321(5894):1357-1361

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Self-assembly of large and small molecules into hierarchically ordered sacs and membranes     

Capito RM  Azevedo HS  Velichko YS  Mata A  Stupp SI 《Science (New York, N.Y.)》2008,319(5871):1812-1816

We report here the self-assembly of macroscopic sacs and membranes at the interface between two aqueous solutions, one containing a megadalton polymer and the other, small self-assembling molecules bearing opposite charge. The resulting structures have a highly ordered architecture in which nanofiber bundles align and reorient by nearly 90 degrees as the membrane grows. The formation of a diffusion barrier upon contact between the two liquids prevents their chaotic mixing. We hypothesize that growth of the membrane is then driven by a dynamic synergy between osmotic pressure of ions and static self-assembly. These robust, self-sealing macroscopic structures offer opportunities in many areas, including the formation of privileged environments for cells, immune barriers, new biological assays, and self-assembly of ordered thick membranes for diverse applications.  相似文献   

Legionella effectors that promote nonlytic release from protozoa     

Chen J  de Felipe KS  Clarke M  Lu H  Anderson OR  Segal G  Shuman HA 《Science (New York, N.Y.)》2004,303(5662):1358-1361

Legionella pneumophila, the bacterial agent of legionnaires' disease, replicates intracellularly within a specialized vacuole of mammalian and protozoan host cells. Little is known about the specialized vacuole except that the Icm/Dot type IV secretion system is essential for its formation and maintenance. The Legionella genome database contains two open reading frames encoding polypeptides (LepA and LepB) with predicted coiled-coil regions and weak homology to SNAREs; these are delivered to host cells by an Icm/Dot-dependent mechanism. Analysis of mutant strains suggests that the Lep proteins may enable the Legionella to commandeer a protozoan exocytic pathway for dissemination of the pathogen.  相似文献   

The genomic sequence of the accidental pathogen Legionella pneumophila     

Chien M  Morozova I  Shi S  Sheng H  Chen J  Gomez SM  Asamani G  Hill K  Nuara J  Feder M  Rineer J  Greenberg JJ  Steshenko V  Park SH  Zhao B  Teplitskaya E  Edwards JR  Pampou S  Georghiou A  Chou IC  Iannuccilli W  Ulz ME  Kim DH  Geringer-Sameth A  Goldsberry C  Morozov P  Fischer SG  Segal G  Qu X  Rzhetsky A  Zhang P  Cayanis E  De Jong PJ  Ju J  Kalachikov S  Shuman HA  Russo JJ 《Science (New York, N.Y.)》2004,305(5692):1966-1968

We present the genomic sequence of Legionella pneumophila, the bacterial agent of Legionnaires' disease, a potentially fatal pneumonia acquired from aerosolized contaminated fresh water. The genome includes a 45-kilobase pair element that can exist in chromosomal and episomal forms, selective expansions of important gene families, genes for unexpected metabolic pathways, and previously unknown candidate virulence determinants. We highlight the genes that may account for Legionella's ability to survive in protozoa, mammalian macrophages, and inhospitable environmental niches and that may define new therapeutic targets.  相似文献   

Cross-linking cellular prion protein triggers neuronal apoptosis in vivo     

Solforosi L  Criado JR  McGavern DB  Wirz S  Sánchez-Alavez M  Sugama S  DeGiorgio LA  Volpe BT  Wiseman E  Abalos G  Masliah E  Gilden D  Oldstone MB  Conti B  Williamson RA 《Science (New York, N.Y.)》2004,303(5663):1514-1516

Neuronal death is a prominent, but poorly understood, pathological hallmark of prion disease. Notably, in the absence of the cellular prion protein (PrPC), the disease-associated isoform, PrPSc, appears not to be intrinsically neurotoxic, suggesting that PrPC itself may participate directly in the prion neurodegenerative cascade. Here, cross-linking PrPC in vivo with specific monoclonal antibodies was found to trigger rapid and extensive apoptosis in hippocampal and cerebellar neurons. These findings suggest that PrPC functions in the control of neuronal survival and provides a model to explore whether cross-linking of PrPC by oligomeric PrPSc can promote neuronal loss during prion infection.  相似文献   

The paradox of the conservation of an endangered fish species in a Mediterranean region under agricultural intensification     

J. Jesús Casas  Juan S. Sánchez-Oliver  Ana Sanz  Miriam Furné  Cristina Trenzado  Melchor Juan  Mariano Paracuellos  María D. Suárez  Francisca Fuentes  Irene Gallego  Carlos Gil  José J. Ramos-Miras 《Biological conservation》2011,(1):253-262

We studied the relative value of natural habitats, river and coastal wetlands, and artificial habitats, irrigation canal and ponds, for the conservation of an endangered fish, Iberian toothcarp, in its southernmost area of distribution, characterised by agricultural intensification. Our results show that the bulk of the population of the Iberian toothcarp is concentrated in irrigation ponds. Natural habitats sustained null or impoverished subpopulations, and individuals showed signs of low metabolic activity. This coincided with the relatively high habitat quality observed in ponds, particularly those with submerged aquatic vegetation, in contrast with the chronic eutrophication of the coastal lagoons. In spite of a generalised aggressive management in the irrigation system, featured by periodic vegetation clearance, desiccation and biocide treatment, the subpopulation of the Iberian toothcarp thrives in it probably thanks to adequate water quality and to an active path dynamics maintained by connectivity through the canal. Agro-environmental measures are discussed for the improvement of this species conservation in natural and artificial habitats.  相似文献   

Stem modeling and simulation of conversion of cork oak stems for quality wood products     

Sofia Knapic  Isabel Pinto Seppä  Arto Usenius  Helena Pereira 《European Journal of Forest Research》2011,130(5):745-751

Recent research is underway to study cork oak (Quercus suber L.) wood potential for production of wood components. A total of 35 stems of young and mature cork oaks were sampled, live sawn into flitches, scanned using VTT’s WoodCIM^®, and the measured data computed by VTT’s PuuPilot software, allowing stem 3D reconstruction. Sawing simulations were run for 0.5 m and 1 m logs and the whole stem. Sawn products were (1) planks, (2) parquet, (3) lamparquet, and (4) external component of multilayer planks. Cork oak stems showed a moderate to small taper (mean 24 mm/m). Curviness varied between straight to significantly crooked stems (mean value 40 mm) Batch yields for the tested products ranged 25–43% and 37–50% for 0.5 m logs of young and mature trees, respectively; for 1 m logs, batch yields ranged 19–41% and 25–54%. When using the whole stem, batch yields were lower, ranging 11–38% and 15–50%. Higher yields were obtained for all log lengths and samples for production of lamparquet, parquet, and multilayer component.  相似文献   

Erratum to: Stem modeling and simulation of conversion of cork oak stems for quality wood products     

Sofia Knapic  Isabel Pinto Sepp?  Arto Usenius  Helena Pereira 《European Journal of Forest Research》2011,130(5):753-753

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Effect of heat treatment of camelina (Camelina sativa) seeds on the antioxidant potential of their extracts     

Terpinc P  Polak T  Ulrih NP  Abramovic H 《Journal of agricultural and food chemistry》2011,59(16):8639-8645

The effect of different heat treatments of camelina (Camelina sativa) seeds on the phenolic profile and antioxidant activity of their hydrolyzed extracts was investigated. The results showed that total phenol contents increased in thermally treated seeds. Heat treatment affected also the quantities of individual phenolic compounds in extracts. Phenolics in unheated camelina seeds existed in bound rather than in free form. A temperature of 160 °C was required for release of insoluble bound phenolics, whereas lower temperatures were found to be optimal to liberate those present as soluble conjugates. The best reducing power and alkyl peroxyl radical scavenging activity in the emulsion was expressed by phenolics which were bound to the cell wall, whereas the best iron chelators and 2,2-diphenyl-1-picrylhydrazyl (DPPH?) radical scavengers were found to be those present in free form. The heat treatment of seeds up to 120 °C increased the reducing power and DPPH? radical scavenging ability of extracts, but negatively affected iron chelating ability and their activity in an emulsion against alkyl peroxyl radicals.  相似文献